Whick ducks should I keep?

Hi all,
I'm new to this forum and would like some advice. We just hatched 4 baby ducks through our 4-H embryology program. We have 2 Pekin, 1 Khaki Campbell, and 1 unknown duck. We've decided we'd like to keep 2 ducks as pets. I'd keep all 4, but husband wouldn't go for that. So I'm trying to decide on which 2 to keep. We live in a suburban neighborhood, and have half an acre. I'm planning on building a coop, with a fence around it for them. We have to teens who are great at helping take care of them. The 2 Pekins are the most personable. They seem to be the most bonded with us. I believe they are a boy and girl, one has pink bill, the other yellow. But not sure if that's a way to tell or not. The other 2 are more skittish. My husband would like to keep the skittish ones because they will be much smaller. He's worried the Pekins will just be too big. I leaning towards the Pekins because of how sweet they are. Does anyone have opinions on which ones would be best as family pets? Easiest to take care of? Also, does anyone know what my little unknown duck is? They were all hatched the same day, and he looks like a Pekin, but is much smaller, with a short, stubby tail. In all pics, he's the one on the right. He's the same size as the Campbell. Thanks!